JP2003149544A - Focusing method, projection exposing method, focusing device and projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focusing method, a focusing device, a projection exposing method and a projection aligner having a spatial optical modulator and made effective when they are used for projection exposure. SOLUTION: Focusing is performed by using the spatial optical modulator constituted to include a plurality of mirrors set so that the inclination of their reflection surfaces can be independently controlled, radiating light in which a mirror pattern carried on the spatial optical modulator is reflected to an object, detecting reflected light on the object and moving the object in accordance with the blur condition of a detected light image. Thus, focusing can be easily performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus aligning method and a focus aligning apparatus, which are performed when performing projection exposure, for example, and a projection aligning method and a projection aligner.

[0002]

2. Description of the Related Art As a projection exposure apparatus for lithography, a DMD (digital mirror device: one of spatial light modulators) including a plurality of mirrors capable of independently controlling the tilt of a reflecting surface is provided, and a control computer is provided. A projection exposure apparatus is conceived in which the micromirrors are each controlled to rotate by the electrostatic solution action by, and a predetermined exposure pattern is carried on the DMD by this rotation control, and the predetermined pattern is projected onto the exposure target.

For example, when forming an integrated circuit pattern on a semiconductor substrate using this projection exposure apparatus, it is necessary to transfer different exposure patterns to the same object many times, and in that case, it is an object. Focusing of the semiconductor substrate is required each time.

[0004]

However, conventionally, there has been no effective focusing method in projection exposure having a spatial light modulator.

The present invention has been made in view of the above problems, and provides a focusing method and a focusing apparatus which are effective for use in a projection exposure having a spatial light modulator, and a projection exposure method and a projection exposure apparatus. The main purpose is that.

[0006]

A focusing method (first invention) of the present invention uses a spatial light modulator including a plurality of mirrors capable of independently controlling the inclination of a reflecting surface, and The target object is irradiated with light reflecting the mirror pattern carried by the spatial light modulator, the reflected light from the target object is detected, and the target object is moved according to the degree of blurring of the detected optical image. It is characterized in that the focus is adjusted accordingly. In this case, the "blur condition" can be defined by the width or size of the bright portion or the dark portion of the light image. According to this focusing method, a light-dark pattern is formed on an object by irradiating the object with light that reflects the mirror pattern carried by the spatial light modulator. Focusing can be easily performed by detecting the degree of blurring of the light image of the light-dark pattern and moving the object in a direction in which the light image of the light-dark pattern becomes clear.

The projection exposure method (second invention) of the present invention is
After performing the focusing by the focusing method of the first invention, the mirror pattern carried by the spatial light modulator is projected and exposed on the object. According to this projection exposure method, since projection exposure is further performed by the spatial light modulator used for focusing, it is not necessary to prepare a special spatial light modulator only for focusing.

A focusing device of the present invention (third invention) is carried by a spatial light modulator including a plurality of mirrors capable of independently controlling the tilt of a reflecting surface, and the spatial light modulator. Light irradiating means for irradiating an object with light reflecting a mirror pattern, light detecting means for detecting reflected light on the object, and the object depending on the degree of blurring of the detected light image. An object moving means for moving an object is provided. According to this focusing device, a light / dark pattern is formed on an object by irradiating the object with light that reflects the mirror pattern carried by the spatial light modulator. Then, the degree of blurring of the light image of the light-dark pattern is detected, and the object is moved in a direction in which the light image of the light-dark pattern becomes clear, so that focusing can be easily performed.

The projection exposure apparatus (fourth invention) of the present invention is
A third aspect of the present invention is provided with the focusing device, wherein the spatial light modulator is configured to be used also for exposure projection on the object. According to this projection exposure apparatus, since the projection exposure is further performed by the spatial light modulator used for focusing,
It is not necessary to prepare a special spatial light modulator only for focusing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a focusing device of the embodiment. This focusing device 100 is configured as follows.

In the figure, reference numeral 10 indicates a light source. The light source 10 is not particularly limited, but a metal halide lamp, a halogen lamp, a xenon lamp, or the like is used. A reflector 20 is installed near the light source 10. The reflector 20 serves to reflect the light from the light source 10 to convert it into focused light and direct it to a DMD (digital mirror device: spatial light modulator) 30 in the next stage. The light from the light source 10 may be collimated and applied to the DMD 30.

The parallel light from the reflector 20 is obliquely incident on the DMD 30. The DMD 30 has a rectangular or rectangular shape as a whole, and has a structure in which micromirrors are arranged in a matrix. The rotation of each of the micromirrors is controlled by the action of an electrostatic field, and the DMD 30 can carry a predetermined mirror pattern by this rotation control. The reflected light from the DMD 30 enters the telecentric optical system 40 at the next stage. The reflected light in this case is light that reflects the mirror pattern carried by the DMD 30.

The telecentric optical system 40 is composed of two plano-convex lenses 41 and 42, although not particularly limited thereto. Then, the object 50 is irradiated with the light reflected by the DMD 30 through the telecentric optical system 40. The light source 10, the reflector 20, and the telecentric optical system 40 form a light irradiation unit. However,
Needless to say, the constituent elements of the light irradiation means are not limited to these.

The object 50 has a flat surface, and a semiconductor wafer is a typical one. The target object 50 is installed on the stage 60. The stage 60 in this case is
It is configured to be movable at least in the optical axis direction of the telecentric optical system 40 by motor power. That is,
The motor and the stage 60 constitute an object moving means. However, it goes without saying that the constituent elements of the object moving means are not limited to these.

The reflected light from the object 50 enters the telecentric optical system 40. Telecentric optical system 4
0 emits the light toward the DMD 30.

The DMD 30 is a telecentric optical system 40.
The light from is reflected and directed toward the light source 10.

A half mirror 70 is installed between the DMD 30 and the light source 10. This half mirror 70
Causes the light from the DMD 30 to be reflected and directed toward the detection unit 80.

Although the detector 80 is composed of a photodiode in the first embodiment, it may be composed of a CMOS instead of the photodiode. The telecentric optical system 40 for detecting the reflected light of the object 50, the DMD 30, the half mirror 70, and the detector 80 constitute a photodetector. However, it goes without saying that the constituent elements of the light detecting means are not limited to these.

Next, an example of the control system 200 of the focusing device 100 of the first embodiment will be described with reference to FIG.

In the figure, reference numeral 110 indicates a computer, which is roughly provided with a central processing unit 111 and a main storage unit 112. The computer 110 has an auxiliary storage device 113,
The input device 114 and the output device 115 are connected.

Of these, the auxiliary storage device 113 stores data and programs. The main storage device 112 temporarily stores data and programs necessary for operating the computer 110. The central processing unit 111 includes an arithmetic unit and a control unit. The arithmetic unit operates on the data sent from the main memory 112. The control device is an arithmetic unit, a main storage device 112, an auxiliary storage device 11
3. Send a control signal to control the input device 114 and the output device 115. As the input device 114, a keyboard, a mouse, a detection unit 80, etc. are connected.
Then, an electrical signal based on the amount of received light is input to the computer 110 from the detection unit 80. As the output device 115, a display, a light source 10, a DMD
30 and a stage moving motor and the like are connected. The computer 110 controls the brightness of the light source 10 and the rotation of the micro mirror of the DMD 30.

In order to perform focusing by using the focusing device 100, the mirror pattern of the DMD 30 is input through the input device 120, or the mirror stored in the auxiliary storage device 113 or the main storage device 112 in advance. The pattern is specified through the input device 120. The mirror pattern in this case is not particularly limited, but it is preferable that a checkered pattern is formed when the object 50 is irradiated.

After the input or designation of this mirror pattern is completed, the light from the light source 10 is transmitted through the reflector 20 to D
Irradiate MD30. The DMD 30 reflects the light, and the light is guided to the telecentric optical system 40. The telecentric optical system 40 enters the light from the DMD 30,
The incident light is emitted toward the object 50.

As a result, a light-dark pattern corresponding to the mirror pattern is formed on the surface of the object 50. The light having the bright-dark pattern passes through the telecentric optical system 40, the DMD 30, and the half mirror 70, and then the detection unit 8 is detected.
Reach 0. The detection unit 80 obtains a light-dark pattern light image, and outputs an electrical signal corresponding to the light and dark (according to the amount of received light) to the microcomputer 110.

The computer 110 includes a central processing unit 11
1, the value of the electric signal is calculated, and when the calculated value is smaller than the reference value (when the degree of blurring is large),
The central processing unit 111 uses the stage 60 and thus the object 50.
Is moved in the direction in which the value of the electrical signal increases (the direction in which the degree of blurring is eliminated) (see FIG. 3).

By moving the object 50 in the direction in which the degree of blurring is eliminated as described above, it is possible to automatically perform focusing.

When using the mirror section of the DMD 30, the entire mirror section may be used, or the mirror section of the DMD 30 may be partially used. When used partially, it is preferable to use two or more parts separated from each other. More preferably, if three or more parts are used, any tilt of the object 50 can be detected, and if the tilt angle of the stage 60 can be controlled to be changed, the tilt of the object 50 is automatically corrected. Because you can do it.

(Second Embodiment) The second embodiment is a projection exposure apparatus, and the focusing device 10 of the first embodiment.
0 is used as it is as a projection exposure apparatus.

In this projection exposure apparatus, the mirror pattern carried by the DMD 30 is also used as an exposure pattern so that the light from the light source 10 is applied to the object 50 through the reflector 20, the DMD 30, and the telecentric optical system 40. It is configured.

Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention.

For example, although the half mirror 70 is provided between the DMD 30 and the light source 10 in the above embodiment, the half mirror 70 is provided between the telecentric optical system 40 and the DMD 30.
Alternatively, the detection unit 80 may be provided between the target object 50 and the light reflected by the half mirror 70 and detected by the detection unit 80.

[0032]

The effects of the typical ones of the present invention will be described. A spatial light modulator including a plurality of mirrors that can independently control the inclination of a reflecting surface is used. Irradiate the object with light that reflects the carried mirror pattern, detect the reflected light at the object, and focus by moving the object according to the degree of blurring of the detected optical image. Since this is done, focusing can be easily done.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical system of a focusing device according to a first embodiment.

FIG. 2 is a configuration diagram of a control system of the focusing device according to the first embodiment.

FIG. 3 is an explanatory diagram of a focusing method of the focusing device according to the first embodiment.

[Explanation of symbols]

10 light sources 20 reflector 30 DMD 40 Telecentric optical system 50 objects 70 Half mirror 80 Detector

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazumi Haga             37-share, 33-53, 3-chome, Kakusen, Komae-shi, Tokyo             Ceremony company New Creation F-term (reference) 2H051 AA10 BA49 BA72 CB07 CB11                       CB14 CC05                 5F046 BA03 DA14 DB05 DB11

Claims (4)

[Claims] 1. A spatial light modulator including a plurality of mirrors capable of independently controlling the inclination of a reflecting surface is used, and light reflecting a mirror pattern carried by the spatial light modulator is applied to an object. A focusing method, which comprises irradiating, detecting reflected light from the object, and moving the object in accordance with the degree of blurring of the detected optical image to perform focusing. 2. A projection exposure method, comprising: performing focus adjustment by the focus adjustment method according to claim 1, and projecting and exposing a mirror pattern carried by the spatial light modulator onto the object. 3. A spatial light modulator including a plurality of mirrors capable of independently controlling the inclination of a reflecting surface, and irradiating an object with light reflecting a mirror pattern carried by the spatial light modulator. For irradiating light, a light detecting means for detecting reflected light on the object, and an object moving means for moving the object according to the degree of blur of the detected light image. Focusing device. 4. A projection exposure apparatus comprising the focusing device according to claim 3, wherein the spatial light modulator is also configured to be used for exposure projection onto the object.